With the advance in medical technology, medical apparatuses having complicated shapes and medical instruments made of special materials are widely used. Therefore, there is a need for a method for cleaning, disinfecting, and sterilizing these medical devices and instruments safely and reliably.
In particular, the quality of cleaning greatly affects subsequent disinfection and sterilization processes, and therefore a method for evaluating the quality of cleaning is of importance.
In recent years, there is demand for establishment of a cleaning evaluation method in medical fields, and standards for evaluation of cleaning draws international attention.
An indirect evaluation method, one of cleaning evaluation methods, is a method in which a contamination model closely resembling actual contaminants is used for evaluation. The contamination model is subjected to a cleaning process to be evaluated, and the degree of cleaning of contaminated medical instruments is evaluated based on how much the contamination model is remained.
As a conventionally used contamination models, there is a model containing a mixture of egg yolk, dye, mucin, and the like (see, for example, “209 points of Cleaning, Disinfection, and Sterilization”, The Japanese Journal of Infection Control 2004 Supplement, p. 55, Medicus SHUPPAN (Japan), Nov. 15, 2004, a non-patent document).
As another contamination model, there is a model obtained by sticking hemoglobin, a major component of blood, and albumin on a stainless steel plate with the use of fibrin (see, for example, International Publication No. WO97/27482).
However, the contamination model described in the above non-patent document contains almost no blood or body tissue components, which are main contaminants, and is therefore apparently different from contamination with blood and tissue components. Thus, this contamination model has a problem of not being able to properly evaluate a cleaning process for a surgical instrument, or the like, contaminated with blood and tissue.
The contamination model described in WO97/27482 contains only blood components, which are easily removed with, for example, an alkali detergent. However, actual main contaminants during surgery contain both blood and tissue components, and are therefore difficult to be removed. Thus, this contamination model also has a problem of not being able to properly evaluate a cleaning process of actual contaminants, which is difficult to be removed.